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Why Athletes Need Different Rates of Fluid Intake

The amount of drinking during rides is related to your sweat rate, but do you actually know how much you sweat? To help you find this out and drink better, we added a small test for you below.


What makes hydration important?

Our body needs fluids mainly to keep the body temperature regulated, make sure our organs function well and to keep the body hydrated. In general, a fluid loss of over 2% of body weight can lead to a serious decline of performance and therefore, the aim should be to limit losses by restoring sufficient amounts of fluids during training and competition.

It is important to realize that the goal should not be to 100% replace sweat losses during competition or training. This would require you to drink amounts that would likely be much higher than your body’s natural instinct and can lead to several negative side effects. At the end of this blog, it will become clear how much you do need to drink.

Your sweat loss per hour will depend largely on several factors including the temperature, your intensity of exercise, humidity, clothing and level of acclimatization and training status (if you are better trained, you are able to regulate your body temperature better). Lastly, also genetics play a big role, some people just simply sweat more than others. Some athletes can even lose up to 3 liters per hour in extreme hot conditions, while others might only lose half a liter in the same conditions. In this test you will set insights in your sweat loss at the temperature and intensity you mostly ride in.


How to test my sweat loss?

You only need 3 ‘ingredients’ before starting: (1) a calibrated weight scale, (2) a dry towel and (3) a small calibrated kitchen scale (optional). Follow the below 6-step protocol to determine your sweat losses;

  1. Visit the toilet and weight yourself straight after (ideally: nude). It is important that this step will be undertaken just before training. Make sure the scale is placed on a stable, flat underground (so not on a carpet).
  2. Perform your training as planned, and note how much fluids and foods you consumed (in EatMyRide app). If you find that hard to remember, you can keep track of it along your ride by using our Garmin widget.
  3. Directly after the training: towel yourself dry, visit the toilet and weight yourself straight after (ideally: nude). For each toilet visit áfter step 1, note 0.3 L.
  4. To calculate how much weight you lost during the training: subtract the weight after training (step 3) from weight before training (step 1). So, fluid loss = step 1 – step 3.
  5. Part of your weight loss can be due to your glycogen depletion. Note that for each gram of glycogen, approx. 2 grams of fluids are stored. Check your glycogen depletion (in EatMyRide app) and subtract this from the fluid loss calculated in step 4.
  6. You can now calculate your sweat loss: (weight loss + liters of fluids ingested – urine production (in liters)) / time (in hours)


Set your new in-ride fluid intake

For athletes with a relative low sweat rate (≤ 1 L / hour): it’s advisable to drink around 300-500 ml per hour. Ranging more towards sweat losses of 0.5 L / hour? Then your aim should be on the low side of this range (towards 300 mL / hour).

For athletes with a medium sweat rate (1 – ≤ 1.5 L / hour): an intake around 750 mLl / hour will meet your required fluid amounts.

For athletes with a high sweat rate (≥ 1.5 L / hour): you will benefit from proper nutrition strategies aiming to be ‘’frontrunner’’ of the dehydration depletion curve. Concrete, aiming to replenish 1 liter per hour, or at least 50% of your sweat rate during your training or race would usually be a realistic guideline. However, this may require training!

Next time you create an in-ride plan in EatMyRide app and reach the page where you add drinking products, click on the hourly fluid intake (which is set by default to 500 mL / hour) and set it to:

(A) 250 ml if you have a low sweat rate (≤ 0.5 L / hour)

(B) 500 ml if your sweat rate is around 1 L / hour

(C) 750 mL / hour if your sweat rate is in the range of 1-1.5 L / hour

(D) 1 liter per hour (or at least 50% of your sweat loss) in case you have a high sweat rate ≥ 1.5 L / hour

The calculated sweat rate should be used as a guideline for comparable rides. It is unlikely that you will be able to strictly follow this original hydration plan for all rides due to race dynamics (speed fluctuations, race situations, other unforeseen circumstances).